Hydrogen is a very attractive fuel because it is clean and can be used to efficiently produce electricity in a fuel cell. The automotive industry expends significant resources in the development of hydrogen fuel cells as a source of power for vehicles. Such vehicles would be more efficient and generate fewer emissions than today's vehicles employing internal combustion engines.
A hydrogen fuel cell is an electro-chemical device that includes an anode and a cathode with an electrolyte between the anode and the cathode. The anode receives hydrogen-rich gas or pure hydrogen and the cathode receives oxygen or air. The hydrogen gas is dissociated in the anode to generate free protons and electrons. The protons pass through the electrolyte to the cathode, where the protons react with the oxygen and the electrons in the cathode to generate water. The electrons from the anode are unable to pass through the electrolyte. Therefore, the electrons are directed through a load to perform work before they are sent to the cathode. The work may be used, for example, to operate a vehicle.
Proton exchange membrane fuel cells generally include a solid polymer electrolyte proton conducting membrane, such as a perfluorosulfonic acid membrane. The anode and the cathode typically include finely divided catalytic particles supported on carbon particles and mixed with an ionomer and a solvent. The combination of the anode, cathode and membrane define a membrane electrode assembly (MEA). The MEA may also include gas diffusion media, a porous layer that is necessary for gas and water transport through the MEA. The catalyst layer may be coated on the diffusion media, for example the catalyst layer may be rolled or painted or sprayed on the diffusion media as a slurry, and then compressed. It is known in the art to sandwich the membrane between two pieces of the catalyst coated diffusion media with the catalyst sides facing the membrane, and then to hot-press to bond the catalyst coated diffusion media to the membrane.